The Design Of The Signal Source Of Capacitance Measurement Instrument

With the rapid development of electronics technology, capacitors are used more and more widely, the capacitance measurement of capacitor is the problem we often meet, so how can we measure the capacitance value conveniently, quickly and accurately is a problem which is worth inquiring deeply. This project is right based on this purpose. Firstly, several theoretical approaches for capacitance measurement are described in the beginning of the paper, and point out the merits and demerits of these methods, in the meanwhile, the paper analyses the present situation of the instrument for capacitance measurement at home and Abroad, and proposes a new kind of design of instrument for capacitance measurement, and the paper also describes the performance and series of Technical Parameters of the new instrument for capacitance measurement.Secondly, the paper introduces the hardware circuit structure of the system in detail and shows the exhaustive circuit diagrams of the main hardware modules, and explains the principles and operation modes of these hardware circuits, these hardware modules include the Signal Generator Circuit of the Direct Digital Frequency Synthesis(DDS), Low-Pass Filter Circuit, Multi-Channel Analog Switch Circuit, High Voltage Amplification Circuit, Power Amplification Circuit, the Detection Circuits of the Current and the voltage, the Circuit of Liquid Display, the Circuit of Infrared Communication and the Design of Power Supply. The paper also briefly introduces the selection principle and the technical parameters of the electronic components which are used in the system, because it is also a part of the research.Thirdly, the paper also states the software design of the system, illustrates the main procedure flow and show the main procedure flow chart of the system, the programming of the main modules is also stated briefly including the programming of the Direct Digital Frequency Synthesis AD9850, the programming of Infrared Communication and the programming of Liquid Display, these statements with time sequence diagram or procedure flow chart are very clear.In the end, the paper analyses the experimental data and error, states the EMC Design of the instrument, and gives some advices about the instrument's improvement in the later. The final result turns out that the performance of the instrument meets expected requirements. The instrument's usage in reality will make capacitance measurement easier.